Yep, turns out it wasn't enabled in the BIOS. Discovered this myself when I clicked the more info today after getting the 'You don't have TPM on this device' from the Windows PC Health Check. That was really confusing. I definitely thought I didn't even have it on my hardware from its messaging the first time around (and even the second time around I wasn't sure until I went through the instructions and checked all the menus on the BIOS).

So if I got confused and thought I didn't have it on my computer, probably many, many other people less tech savvy than me were similarly confused (or just wouldn't bother. BIOS changes can be weird and scary anyway, Windows couldn't even give good instructions on that part because BIOS menus tend to be pretty different).